Bit with interchangeable blade



April 22, 1952 H. 0. WILSON BIT WITH INTERCHANGEABLE BLADE Filed Dec. 11, 1946 Patented Apr. 22, 1952 BIT WITH INTERCHANGEABLE BLADE Harry 0. Wilson, Sherman Oaks, Calif; assignor to Robert H. Clark, Los Angeles, Calif.

Application December 11, 1946, Serial No. 715,424 Claims.. (Cl. 145-126) This invention has to do with a bit with interchangeable blades and it is a general object of the inventio to provide a simple, practical, easily operated bit structure in which the cuttin blade can be removed or replaced at will to replace worn parts or to vary the size of the bit.

Bits such as are used for drilling or boring wood, or the like, are commonly of fixed size and are of unitary construction so that only one size of hole can be drilled with any particular bit and the bit as a whole is impaired when its cutting parts are impaired or dulled. Adjustable bits have been proposed and used, such a bit being disclosed and claimed in my copending application entitled Bit With Adjustable Cutting Blade. However, such structures are somewhat'complex and correspondingly expensive of manufacture.

It is a general object of my present invention to provide a bit construction involving a simple sturdy shank with a head carrier and a feed screw, and adapted to receive cutter heads of various sizes so that by applying a head of the proper size any desired size of bore can be obtained.

Another object of the present invention is to provide a cutter head for a bit of the character referred to which is simple, effective, and inexpensive of construction making it practical to supply a single or common shank with a plurality of cutter heads of different sizes to be used at will to out different size bores.

Another object of the present invention is to provide a simple, effective, practical construction by which a cutter head is applied to a shank so that it is efiectively and dependably held in a most advantageous manner for operation and yet can be easily and quickly detached when desired.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred ,iorms and applications of the invention, throughout which description reference ismade to the accompanying drawings, in which:

Fig. 1 is a side elevation of a typical bit embodying my invention, showing it in the course of drilling a hole through a body of wood. Fig. 2 is a view of the bit taken as indicated by line 2-2 on Fig. 1. Fig. 3 is a detailed vertical sectional view of the bit construction, being a view taken as indicated by line 33 on Fig. 2. Fig. 4 is a bottom plan view of the bit being a view taken as indicated by line 44 on Fig. 3. Fig. 5 is an enlarged side elevation of the cutter head that I have provided, showing it viewed as it appears in Fig. 1 of the drawings, and Fig. 6 is a View similar to Fig. 3, showing another form of the invention.

The bit of the present invention involves, generally, an elongate shank A, a cutter head B, a head carrier C projecting from the shank, a feed screw D projecting from the carrier C, and means E holding the head engaged on the carrier.

The shank A is an elongate bar or shaft that may be of any desired size or length. Ordinarily the shank will be operated by a brace or through the chuck of a drill, and therefore it is preferred to provide it at its upper end with a polygonal portion ID as clearly shown in Fig. 1 of the drawings. In the preferred form of the invention the shank A is round in cross section and uniform in size from the polygonal part I!) to its outer or lower end where it is provided with or terminates in a shoulder H. In the form of the invention illustrated in Figs. 1 to 5 of the drawings the shoulder is a fiat shoulder lying in a plane normal to the longitudinal axis of the shank A whereas in the form of the invention illustrated in Fig. 6 the shoulder H is tapered so that it is wedgeshaped or conical in form and is concentric with.

the longitudinal axis of the shank.

The head carrier C projects downwardly from the lower or shouldered end of the shank and it is preferably in the nature of an integral continuation of the shank somewhat smaller in diam eter than the shank.

The feed screw D projects downwardly from or beyond the carrier 0 and it is preferably a tapered screw with its upper or large end corresponding in size or diameter with the carrier 0'. It is preferred that the screw D be integrally joined with or formed as an integral continuation of the carrier C.

The head B is a fiat or substantially flat discshaped unit carried by or mounted on the carrier C. The cutter head is characterized by an outer peripheral wall or edge [5 concentric with the axis of the shank or of the carrier on which the head is mounted, by a cutting edge 16 facing forward or in the direction in which the tool operates, and by a depending spur I! that acts ahead of the edge I6 to make an annular cut inthe material M being bored, leaving an upstanding round boss l8 of material, the top of which is cut away by the edge It as the tool op-' erates. The cutter head has a central opening 20 extending through it to accommodate the carrier C and the opening 20 is pitched or in so that the edge 16 is spaced somewhat below the bottom of the head, as clearly shown in Figs. 1 and 5 of the drawings.

A throat opening or chip passage !30:is:p rovided in the head immediately forward oftheli p 23 to provide free passageof chips or cuttings made by the edge as the tool operates. 'Inthe case illustrated the throat 30 is a substantially radial opening or passage formed in the blade andextendingfrom the opening to themriphery l5.

The spur I1 is a downwardly projecting bladelike part with a sharpened edge 3i which serves to effectively establish anarrow annular cut 32 in the material M ahead of the edge l6,'as the tool operates. The spur is preferably an integral projection or'extension of the disc-shaped head as I have shown'in the drawings.

The means E which I provide for holding the head engaged with the carrier serves to releasablyhold the head on the'carrier. The means E is preferably established by cooperating threads on the head and carrier. In the preferred form of the invention illustrated in the drawings the carrier C is externally threaded while the opening 20 in the head B is internally threaded to receive the threads of the carrier. I prefer, in practice, to form the thread of the carrier as a continuation of the thread of the screw D as I have shown in the drawings.

' In the preferred form of my invention I provide a central boss 40 on the upper side or top of the cutter head '3 and I provide the boss with a shoulder to cooperate with the shoulder H of the shank. In the form of the invention illustrated in Figs. 1 to 5, inclusive, the top of the boss 40 is flattened or provided with a fiat shoulder lying in a plane normal to the axis of the shank.

In the .form of the invention illustratedin 'Fig. 6 I-s'how a tapered socket entering or extending into the cutter head 3 from the top of the boss 40 to form a tapered seat orshoulder M in or on which the shoulder i i of the shank seats. The tapered engagement between-the shank and cutter head shown in Fig. 6 possesses certain advantages over that shown in the other form of theinvention, in thatit provides Wedging engagement between the head and the shank positively preventing accidental displacement or loosening of the head from the shank. H In practice my construction is so simple and inexpensive that it makes it practical to supply a single shank A with a plurality of cutter heads B of different sizes, it being far cheaper to supply a single shank and a collection of different sized heads than it is to provide a plurality of shanks or bits of different sizes. In using the structure the operator selects the cutter head that will form the desired bore and applies that head to the shank by simply screwing it onto the carrier C which projects from the :shank until the head is tightly seated against the shoulder =.of the shank sired size.

advantageous manner. spur i I I.

4 with the fiat shoulder shown in Figs. 1 to 5 or the tapered shoulder shown in Fig. 6.

As the structure is rotated in the manner common to bits the feed screw leads the bit into the work while the spur makes the annular cut leaving the part I8 to be shaved or cut away by the edge It. When the out has been completed and it is desired to make a bore of a different size, it

is a 've'ry=siinplematter to unscrew the'cutter head from the carrier C to separate the head and shank and to thereafter apply a cutter head of the de- Further, when the cutter is detached from the shank the cutting edge I6 is readily accessible so'that'it can be sharpened in a most This is also true of the Having described only typical, preferred forms and applications of'my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the'scope of the following claims.

Having described my invention, I claim:

1. A bit for boring a hole including, an elongate shank, a substantially flat disc-shaped cutter head having a depending blade portion,=a head carrier projecting from one end-0f the shank, a feed screw projecting from the carrier, and means whereby the head is releasably retained on the carrier in a plane inclined relative to a plane normal to the longitudinal axis of the shank, the top side of the head having aflat and smooth portion adapted to act on cuttings in the bore as the bit advances to discharge'cuttings from the bore.

2. A hole boring bit of the character described including, an elongate shank having a fixed shoulder at its lower end, a substantially flat discshaped cutter head, a head carrier projecting from said end of the shank beyond the shoulder, a feed screw projecting from'the outer end of the carrier, and means whereby the head is releasably retained on the carrier in an inclined position relative to a plane normal to the longitudinal axis of the shank and in engagement with the, shoulder including cooperating threads on the head and carrier, the head having a depending cutting blade and the upper side of thehead acting to discharge cuttings from the hole made-by the blade.

3. A hole boring bit of the character described including, an elongate shank having a fixed shoulder at its lower end in a plane normal to the longitudinal axis of theshank a substantially flat disc-shaped cutter head with a depending cutting blade, a head carrier projecting from said end of the shank beyond the shoulder, a feed screw projecting'from the outer end of the c'ar-' rier, and means whereby the head is releasably retained on the carrier in a plane inclined relative to a plane normal to the longitudinal axis of the shank and in engagement with the shoulder including cooperating threads onthe headv and carrier, there being a boss on the upper side of the head with a surface cooperatively engaging the shoulder, the top of the head having a flat and smooth portion acting on cuttings in the bore as the bit advances to discharge cuttings from the bore.

4. A bit of the character described including, an elongate shank having a fixed tapered shoul-. der at its lower end, a substantially fiat disc'- shaped cutter head with a depending cutting blade, 2. headcarrier projecting from-said end of the shank beyond the shoulder, a feed screw projecting from the outer end of the carrier, and means whereby the head is releasably retained on the carrier in a plane inclined relative to a plane normal to the longitudinal axis of theshank and in engagement with the shoulder including cooperating threads on the head and carrier, there being a boss on the upper side of the head with a surface" cooperatively engaging the shoulder. I v 1 5. A bit of the character described including, an elongate shank having a fixed tapered shoulder at its lower end. a substantially fiat discshaped cutter head with a cutting edge, a head carrier projecting from said end of theshank beyond the shoulder, a feed screw projecting from the outer end of the carrier, and means whereby the head is releasably retained on the carrier in a plane inclined relative to a plane normal to the longitudinal'aiiis of the shank and in engagement with the shoulder including cooperating threads on thehead and carrier, there being a boss on the upper side of the head and having a tapered socket for receiving the shoulder.

HARRY C. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

